The present invention relates generally to industrial implements having an engine, a hydraulically operated working tool apparatus, and an interlock controlling the operation of the engine and the working tool apparatus and, more particularly, to a service override feature for the interlock on a skid steer loader.
It is desirable that the operator of industrial implements such as skid steer loaders remain seated in the operator seat with an operator restraint mechanism, such as a seat belt, engaged to restrain the operator from leaving the seat. By sensing both the presence of the operator in the seat and the engaging of the operator restraint mechanism, a controller can determine when the operator restraint mechanism is not being utilized in conjunction with the operator coming and going from his seat.
Seat interlocks for skid steer loaders, such as described in U.S. Pat. No. 4,385,863, issued to Ray C. Minor on May 31, 1983, merely sense the presence of the operator in the seat and operate to disable the hydraulic system when the operator is out of the seat. However, it is desirable to tie in the operation of the operator restraint mechanism with the seat sensor to control the operative functions of the loader and, thereby, encourage the use of the operator restraint mechanism.
An interlock mechanism requiring the sequencing of the seat and seat belt switches to enable the engine to be started or to enable the operation of the hydraulic system causes some difficulty whenever it is desireable to service the loader engine or other items such as drive chain adjustment or neutral adjustment for the propulsion controls. To require the operator to sit in the seat and then fasten the seatbelt each time he wishes to start the engine is too cumbersome and inconvenient during servicing activities, particularly when it is necessary to start and restart the engine a number of times. Servicing the engine, however, does not require the operation of the working tool apparatus. Accordingly, it would be desireable to provide a service override feature on such a loader interlock that would permit the engine to be started without sequencing the seat and seat belt switches, yet not permit the operation of the hydraulic system.